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haskellrecursionstack-overflow

Why doesn't this cause stackoverflow?

In 8.hs I define

digitProduct [] = 1
digitProduct (c:rest) = (read [c] :: Int) * digitProduct rest

Then inside ghci, I run

digitProduct $ take 10000 $ repeat '9'

And it produces a result:

-3633723290617080191

I would've imagined that a recursion of 10000 would've caused a stackoverflow. Also, my recursion isn't a tail call. What's going on here?

Solution

  • Nothing special is going on. 10,000 is just not enough to fill the stack. I get a stack overflow in ghci when I replace take 10000 with take 100000000.